(Not Applicable)
(Not Applicable)
The present invention relates generally to an antenna assembly, and more particularly to a design for an antenna assembly for a cellular telephone that is safe for the user.
Recent newspaper, radio and television stories are publicizing the possibility of dangers from the current cellular telephone antenna designs. The current antenna designs are variations of a half-wavelength dipole or a quarter-wavelength monopole on a ground plane with the use of inductive coils and/or capacitive top loading to reduce the length of the antenna and to achieve a satisfactory impedance match. These designs all radiate omni-directional in the azimuth plane, which means that the user""s head, and hence brain, is irradiated with an amount of electromagnetic (EM) radiation equal to that in any other direction in azimuth which may be unsafe, particularly with repeated exposure.
Published studies have shown that the curvatures of the skull bones and brain matter focuses to some extent on impinging EM radiation creating xe2x80x9chot spotsxe2x80x9d within the brain. Recently, the media has been focusing on the possible increased risk to the user of developing a brain tumor. However, other medical problems are also possible, including increased risk of stroke, Parkinson""s disease and Alzheimer""s Syndrome.
Thus, a need exists for a cellular telephone antenna design which decreases the radiation near a user""s head and is therefore safer for the user.
In accordance with aspects of the invention, an antenna assembly which is safer for a user of an electronic communications device, such as a cellular telephone, is disclosed. The electronic communications device includes a housing and a communications port. The invention includes a first active member (e.g., an antenna) that is in communication with the communications port. The invention also includes a field diverter which is connected to the first active member and reduces radiation adjacent to the electronic communications device.
In accordance with other aspects of the invention, the field diverter is made up of a second active member opposite (e.g., substantially parallel to) the first active member. Preferably, the pair of active members (i.e., the first active member and the second active member) are substantially identical to each other, for example, both are monopole antennas or both are dipole antennas. In various embodiments, the pair of active members are extendible. In other embodiments, the pair of active member are extracted from the housing. There is about a 90-degree phase differential between the two active members.
In accordance with still other aspects of the invention, the pair of active members are connected by an active connecting member (e.g., an arm). Preferably, the active connecting member is rotatable such that the second active member rotates about the first active member. In various embodiments the active connecting member is extendible. The active connecting member includes a power divider which splits power from the communications port substantially equally between the pair of active members such that the pair of active members have input voltages equal in amplitude.
In accordance with further aspects of the invention, there is also an inactive connecting member opposite (e.g., substantially parallel to) the active connecting member. Preferably, the inactive connecting member is made of non-metallic and/or dielectric materials.
In accordance with still further aspects of the invention, there is a transmit enable switch that is only operable when the second active member is in a transmit detented position. There may also be a transmit disable switch that disables transmissions from the electronic communications device when the pair of active members are not properly spaced from each other. The functionality of the transmit enable switch and transmit disable switch can be combined into a single switch. Preferably, the electronic communications device is always capable of receiving an incoming signal (e.g., an incoming call).
In accordance with yet further aspects of the invention, the antenna assembly is constructed to decrease radiation in an area where a user""s head is located, wherein an azimuth pattern for the antenna assembly includes a notch in the azimuth pattern near the area where the user""s head is located. The notch forms a sector of about 55 degrees in which the radiation is decreased (e.g. the radiation in the sector is decreased by at least 20 dB). The radiation is increased (by about 3 dB) in an area away from the user""s head.